Conductive transparencies have a variety of uses. For example, a conductive transparency can be used as a canopy, window or windshield of a flying vehicle (e.g., an aircraft), or as an armor-grade transparency of a ground vehicle, such as the windshield or windows of an AM General HMMWV (“HUMVEE®”). HUMVEE® is a registered trademark of AM General, LLC. When used as an aircraft canopy, window or windshield, or as an armor-grade transparency of a ground vehicle, it is beneficial for the transparency to have defogging and de-icing capabilities. For example, defogging and de-icing can be accomplished by, among other things, heating the transparency (e.g., window or windshield) via the conductive portion of the transparency, such as an indium tin oxide (ITO) layer or electroplated grid, thereby preventing or reducing the formation of ice or condensation, or thawing ice or evaporating condensation that has already formed, on the transparency. An ITO layer is sometimes included as the conductive portion of armor-grade transparencies.
It is also beneficial for conductive transparencies to be able to prevent or reduce the buildup of static charge and to have electromagnetic interference (EMI) shielding capabilities, thereby shielding electronic systems within the vehicle from electromagnetic interference. The buildup of static charge can be prevented or reduced by draining or dissipating the static electricity that can build up on the transparency as a result of precipitation static and/or lightning strikes. Additionally, EMI shielding can be provided by preventing or reducing the transmission of disruptive electromagnetic radiation (i.e., electromagnetic radiation that interferes with electronic systems) through the transparency.
Typical aircraft transparencies include conductive portions that are expensive to produce, and often are prepared with a low percent yield. For example, the conductive portion of the transparency may be a woven wire mesh. Further, some aircraft windows include an electroplated grid, which requires the application of an organic primer, copper, photomask and resist, and the electroplating of copper and nickel. Each of these process steps adds to the complexity of the process, increases manufacturing expense and increases the risk of handling damage. For example, typical aircraft transparencies and armor-grade transparencies are produced using vacuum deposition processes that require expensive chambers, are time consuming, and may, themselves, create defects in the transparency or its coatings.
Additionally, existing aircraft transparencies often do not provide satisfactory de-icing, static dissipation, and/or EMI shielding capabilities, and some of the conductive transparencies that are currently in use have unsatisfactory lifetimes. Accordingly, there is a need for durable conductive aircraft transparencies and conductive armor-grade transparencies that can be configured to provide de-icing, static dissipation and/or EMI shielding properties, and that can be produced by simpler and more economical methods than traditional industrial techniques, such as electroplating, vacuum deposition, and the formation of woven wire mesh.